Method for the continuous casting of metal slabs



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METHOD FOR THE ccmmuous CASTING OF METAL sums Filed Nov. 6', 1947 r a Sheets-Sheet 2 Amy/u A Patented Jan. 31, 1950 METHOD FOR THE CONTINUOUS CASTING F METAL SLABS Irving Rossi, Morristown, N. J.

Application November 6, 1947, Serial No. 784,466

4 Claims. (Cl. 22--200.1)

This invention relates to methods for the continuous casting of metal slab, it being understood that the term slab as used herein, denotes a rectangular section having a. width which greatly exceeds the thickness thereof. A typical slab for which the method is well adapted might have dimensions in the neighborhood of 9" x for example.

Slabs of these dimensions have not heretofore been cast successfully by continuous casting methods, and it has been necessary, therefore, to roll such slabs from ingots or billets of very much larger dimensions. The advantages of being able to cast such slabs directly and continuously will be obvious, and it is an object of the present invention to provide a method for so doing.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 1 is a. top plan view, partly in section.

Figure 2 is a section on the line 2-2 of Figure 1.

Figure 3 is a section on the line fltl of Figure 1.

Figure l is a. top plan view, partly in section showing a. modified form of apparatus.

According to the present invention, all of the heat which is withdrawn from the molten metal to cause solidification thereof is withdrawn through one surface of the slab by means of a chilled flat mold wall which is opposed to one surface of the slab only. As a result, crystal growth proceeds in a direction substantially perpendicular to said chilled mold wall and toward an opposite mold wall maintained at a temperature such as to prevent any appreciable withdrawal of heat. Said opposite mold wall serves to limit the crystal growth proceeding outwardly from the chilled mold wall, however, and forms and smooths the opposed slab surface as the slab is withdrawn continuously therefrom.

Referring to the drawings, the apparatus comprises a mold block ll of any suitable heat resisting material such as graphite, said block having a cavity 2 in its upper portion serving as a reservoir in which a pool of molten metal may be maintained, such molten metal being supplied continuously from a suitable holding furnace (not shown) through a. pipe or tube 3, the discharge end of which should be submerged in the molten metal pool. The said mold block may be supported in any suitable manner, as by a base plate 4.

Extending downwardly through the bottom of the mold block is a rectangular passage 6 registering with a similarly shaped but somewhat larger aperture 1 in the base plate. A. water cooled shell Bprojects downwardly into the passage 6, the said shell being so formed, in the preferred embodiment illustrated in Figures 1, 2 and 3, as to permit the simultaneous casting of two separate slabs 5, 5'. Thus the shell comprises two relatively thin, fiat side walls 9 and I0, end walls H and i2 and a bottom wall I3 and within this shell are mounted two baflle plates 14 and 15. The lower edges of the bafile plates are spaced from the bottom wall of the shell in order to permit cooling water to circulate within, the mandrel. Suitable inlet and outlet connections are provided for water circulation, such connections being preferably adapted to introduce the cooling water into the space between the bafiles so that it may circulate in the direction indicated by the arrows in Figure 3.

The shell is mounted to slide in guide members such as channels it and H, also preferably made of graphite, in order that vertical reciprocating motion may be imparted to the shell during the casting operation, such reciprocating motion to be preferably in accordance with the teachings of Junghans Patent No. 2,135,183. That is, the shell which provides the cooling surface and which, therefore, corresponds to the chilled mold of the Junghans patent, would be reciprocable, moving downwardly with the slab at the same rate at which the slab is being withdrawn, and moving upwardly at a more rapid rate.

It will be noted that the longitudinal flanges of the channels I [i and H, together with the side walls 9 and ill of the shell and the parallel walls 118 and W of the passage 6 define two mold passages 2|) and M, in each of which a slab may be cast. In each of these mold passages the only chilled surface is that provided by the walls 9 and id, for the channels (6 and H are kept hot by the pool of molten metal, and under most conditions the heat from the molten metal will also keep the mold block I at a temperature sufficient to prevent any appreciable withdrawal of heat through the walls 18 and I9. However, the mold block may be provided with passages 22 to receive suitable heating elements by means of which the block may be maintained at any desired temperature.

As a result of this construction, crystal growth proceeds from the chilled walls 9 and i0 toward the walls l8 and I9, so that, as indicated in Figure 3, the wall thickness of the slab increases gradually until the crystals engage the walls I! and It. It will be understood, of course, that the solidified slab is withdrawn continuously, and this movement causes the forming crystals along the outer surfaces of the slab to be smoothed by the walls 18 and 19 as final solidification takes place. As final solidification takes place, slight shrinkage also takes place so that the friction of the solidified metal against the walls of the mold passage is not serious.

If desired, the bottom wall 63 of the shell may be provided with a plurality of apertures 23 suitably spaced and angled to permit some of the cooling water to spray against the inside walls of the emerging slabs. Likewise, spray pipes 24 may be located below the point of emergence of the slabs from the mold passage to spray cooling water against the outside walls of the slabs. These sprays serve to carry ofi the residual heat remaining in the slabs after the solidification of the molten metal which results entirely from the withdrawal of heat through the chilled surfaces 9 and it of the shell.

A modified form of apparatus adapted for easting a single slab is illustrated in Figure 4 in which a single mold passage at is formed between the chilled plate 32 of the shell and he wall 33 of the mold block, with the ends of the passage being formed by the channels 34 and 35 in which the shell slides as previously described. In addition to the plate 32, the shell comprises a back plate 36 and end plates 31 and 38 with a bafiie 39 to control the circulation of cooling water as before. The operation is as previously described, with crystal growth proceeding outwardly from the chilled surface 32 toward the wall 33 which is heated by the pool of molten metal in the cavity of the mold block.

It will be understood that the invention may be variously modified'and embodied within the scope of the subjoined claims.

I claim as my invention:

1. A method for the continuous casting of metal slab which comprises shaping one face of the slab by means of a water cooled fiat surface which constitutes the sole means for the withdrawal of heat to cause solidification of the molten metal whereby crystal growth proceeds outwardly from said surface, limiting the outward crystal growth by means of a mold wall spaced from said fiat surface, maintaining said mold wall at a temperature sufiicient to prevent appreciable withdrawal of heat therethrough, and continuously withdrawing the solidified slab, the relative movement between the slab and said mold wall serving to smooth the outwardly growing crystals as final solidification takes place.

2. A method for the continuous casting of metal slab which comprises shaping one face of the slab by means of a water cooled fiat surface which constitutes the sole means for the withdrawal of heat to cause solidification of the molten metal whereby crystal growth proceeds outwardly from said surface, limiting the outward crystal growth by means of a mold wall spaced from said fiat surface, maintaining said mold wall at a temperature sufficient to prevent appreciable withdrawal of heat therethrough, continuously withdrawing the solidified slab,'the relative movement between the slab and said mold wall serving to smooth the outwardly growing crystals as final solidification takes place, and reciprocating said water cooled fiat surface in timed relation to the withdrawal of the solidified slab such that said surface moves downwardly with the slab at the same rate at which the slab is withdrawn, and moves upwardly at a more rapid rate.

3. A method for the continuous casting of metal slab which comprises maintaining a pool of molten metal in a mold block having a mold passage extending therethrough, withdrawing heat to solidify molten metal entirely through a water cooled fiat surface extending into said mold passage on one side thereof so that crystal growth proceeds entirely outwardly from said surface toward the opposed wall of said mold passage and is limited thereby, and withdrawing the solidified slab continuously from said passage, the relative movement between the slab and wall of the mold passage serving to smooth the outwardly growing crystals as final solidification takes place.

4. A method for the continuous casting of metal slab which comprises maintaining a pool of molten metal in a mold block having a mold passage extending therethrough, withdrawing heat to solidify molten metal entirely through a water cooled fiat surface extending into said mold passage on one side thereof so that crystal growth proceeds entirely outwardly from said surface toward the opposed wall of said mold passage and is limited thereby, withdrawing the solidified slab continuously from said passage, the relative movement between the slab and wall of the mold passage serving to smooth the outwardly growing crystals as final solidification takes place, and reciprocating said water cooled fiat surface in timed relation to the withdrawal of the solidified slab such that said surface moves downwardly with the slab at the same rate at which the slab is withdrawn, and moves upwardly at a more rapid rate.

IRVING ROSSI.

REFERENCES CITED The following references are of record in the file of patent:

UNITED STATES PATENTS Number Name Date 1,476,967 Hedly Dec. 11, 1923 1,548,618 Lane Aug. 4, 1925 1,943,351 Stockfleth et a1. Jan. 16, 1934 2,007,301 Lemieux July 9, 1935 2,135,183 Jun"'hans Nov. 1, 1938 2,166,006 Harbord et a1. July 11, 1939 2,225,416 Junghans Dec. 17, 1940 FOREIGN PATENTS Number Country Date 705,767 Germany May 9, 1941 

